Create a basic doze dream in SystemUI.

The doze dream is not configured by default.

When configured, the doze dream does not show anything by default.
It teases a dark version of the keyguard (showing only the time
and notifications) when a notification arrives or significant motion
is detected.

Bug:15863249
Change-Id: Icfceb054d35d6fd4d9178eda7480e2464873ca4b
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/ExpandableView.java b/packages/SystemUI/src/com/android/systemui/statusbar/ExpandableView.java
index 4d4a8ab..c3fb83c 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/ExpandableView.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/ExpandableView.java
@@ -167,6 +167,15 @@
     }
 
     /**
+     * Sets the notification as dark. The default implementation does nothing.
+     *
+     * @param dark Whether the notification should be dark.
+     * @param fade Whether an animation should be played to change the state.
+     */
+    public void setDark(boolean dark, boolean fade) {
+    }
+
+    /**
      * @return The desired notification height.
      */
     public int getIntrinsicHeight() {